Dear R-users,
I've been comparing different types used in quantile() function and I
found a thing I don't understand.
When n*p[i] is less than 1, most types return the smallest vector
element, while type 7 interpolates between the smallest and the second
smallest element. Other types, that generally also use linear
interpolation, don't do it.
Example:
> inp
[1] -0.762498 0.785960 1.588090 1.059290 0.022041 0.423641 0.992247
[8] -0.240316 -0.231395 0.762765 -1.474740
> quantile(inp, p, type=6)
0.1% 0.5% 1% 2% 5% 10% 50%
-1.474740 -1.474740 -1.474740 -1.474740 -1.474740 -1.332292 0.423641
> quantile(inp, p, type=7)
0.1% 0.5% 1% 2% 5% 10% 50%
-1.467618 -1.439128 -1.403516 -1.332292 -1.118619 -0.762498 0.423641
> quantile(inp, p, type=8)
0.1% 0.5% 1% 2% 5% 10% 50%
-1.474740 -1.474740 -1.474740 -1.474740 -1.474740 -1.142360 0.423641
Is there an explanation to it? I couldn't find anything in the function
description.
Thanks in advance,
Anna